A significant and free update Fritz chess engine, increasing strength by about 120 Elo points at shorter time controls.
From the developer's website we can read, among other things:
"The classic Fritz 18 engine has a manually optimised rating function and achieves a playing strength of about 3300 ELO. In the new Fritz 18 Neuronal engine, the rating function has been replaced by a fast neuronal network (NNUE), enabling play 120 ELO points better, (i.e., achieving about 3,400+ ELO).
(...) The special feature of NNUEs is that they are relatively small, and can be efficiently evaluated incrementally during the search. NNUEs do not require a GPU - the instruction set extensions of modern CPUs (SSE2, AVX2 or AVX-512) are sufficient. The fastest version of Fritz 18 Neuronal, which uses the AVX-512 instruction set, achieves approximately the same number of nodes (NPS) as Fritz 18; the AVX2 version (all modern CPUs) is only 5% slower.
A total of approx. 5 million games were played, and from these, 400 million rated positions were generated for training the net. The first net was trained based on evaluations from 200,000 self-play games of Fritz18, then in a further 80 training iterations, a total of about 300 intermediate versions of the net were tested and the best net was chosen step by step."
Fritz 18 can be purchased from the company's ChessBase store.